Abstract
Polyamine chelating adsorbents have a good removal effect on dye wastewater. In this study, small molecule triethylenetetramine and macromolecular poly(ethylene imine) were selected as aminated reagent, and two kinds of aminated chitosan microspheres, TETA-CTSms and PEI-CTSms, were obtained by emulsion cross-linking method. The microspheres were fully characterized by FTIR, SEM, XRD, EDS and TGA. EDS results showed that the N content of the PEI-CTSms and TETA-CTSms microspheres increased significantly after the cross-linking reaction and can reach 5.7 wt% and 7.3 wt%, respectively. Adsorption experiments confirmed that TETA-CTSms and PEI-CTSms showed greater adsorption characteristics for anionic dye reactive yellow (RY) in aqueous solutions compared with CTSms, and the adsorption capacity per unit area was increased by 39.11% and 88.56%, respectively. The adsorption capacity of aminated microspheres for RY decreased with the increase of pH. The adsorption kinetics conformed to the pseudo-second-order model, and the adsorption process was in accordance with the Langmuir isotherm model. The negative value of ΔG confirmed that the adsorption process was spontaneous, and the dye adsorption was a multiple process dominated by chemical chelating and physical adsorption.
Highlights
Dye wastewater has become a serious problem that restricts rapid economic development, affects people’s health and seriously damages the environment [1,2,3]
methylene blue (MB) and reactive yellow (RY) were used as adsorption object in the adsorption experiment; the concentration of them in the solution was determined by using UV analysis, and the pH value of dye solution was adjusted by HCl and NaOH aqueous solution
In the adsorption process of three microspheres for MB and RY, the value of the linear correlation coefficient R2 obtained by pseudo-second-order kinetic is large, and the equilibrium adsorption capacity Qexp obtained by fitting is close to the experimental value, indicating that the adsorption is mainly controlled by chemisorption [25]
Summary
Dye wastewater has become a serious problem that restricts rapid economic development, affects people’s health and seriously damages the environment [1,2,3]. Chemical process of preparing aminated chitosan microspheres. Polyamine chelating adsorbents have many advantages, such as good removal effect, strong selectivity, high efficiency of separation and recovery, reliable operation and so on. Chitosan is mainly a linear polysaccharide composed of glucopyranose units It is a derivative obtained by deacetylation of chitin. Jia et al [18] prepared triethylenetetramine aminated chitosan derivatives used epichlorohydrine as a medium through two reactions. Jing et al [20] prepared poly(ethylene imine) aminated chitosan derivatives with the aid of cross-linking agent glutaraldehyde by two reactions. In order to reduce the amount of solvents and reagents used in the multi-step experiment, in this work, aminated chitosan materials were prepared by simultaneous emulsion cross-linking of polyamine reagents.
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